1298 
the star’s velocity in the direction towards the observer be w. Then 
from the law of motion of the star we can derive an equation : 
ds flyer ee 
The light emitted by the star at the time ¢ reaches the observer 
at the time T=t + 4/,—-au. In Ritz’s theory we have, neglecting 
the second and higher powers of “'., a= 4/2. In other theories we 
have «=-0. If now we put Tt, =, +> le , we have 
uf(r—rt, + au) or u P(r oe ee 
The function gy will differ from f, unless ew be immeasurably 
small. Therefore if one of the two equations (1) and (2) is in agree- 
ment with the laws of mechanics, the other is not. Now « is far 
from small. In the case of spectroscopic doubles « also is not small, 
and consequently «&% can reach considerable amounts. Taking e.g. 
r 
sve 
u = 100 ——, and assuming a parallax of 0".1, from which 4/e = 33 
SéC * 
years, we find approximately «u = 4 days, i.e. entirely of the order 
of magnitude of the periodic time of the best known spectroscopic 
doubles. 
Now the observed velocities of spectroscopic doubles, 1. e. the 
equation (2), are as a matter of fact satisfactorily represented by a 
Keplerian motion. Moreover in many cases the orbit derived from 
the radial velocities is confirmed by visual observations (as for 
J Equulei, § Herculis, ete.) or by eclipse-observations (as in Algol- 
variables). We can thus not avoid the conclusion «== 0, i.e. the 
velocity of light is independent of the motion of the source. Rrrz’s 
theory would force us to assume that the motion of the double stars 
is governed not by Nerwron’s law, but by a much more complicated 
law, depending on the star’s distance from the earth, which is 
evidently absurd. | 
Chemistry. — ‘“Lquilibria in ternary systems’. VI. By Prof. F. A, 
H. SCHREINEMAKERS. 
In a manner similar to that in which, in the previous communi- 
cations, we considered the saturation line under its own vapour 
pressure we can also consider the conjugated vapour line. Instead of 
the two-phase complex /“-++ LZ we now, however, take, the complex 
F4 Gand if in the three-phase equilibrium /#’+ L + G no phase 
reaction occurs, we must in the conversion of + G again 
distinguish three cases. 
